This is from the dead as a ghost town itch table top forum. This is response to a portion of the greater question and assumptions about old school play.
"10. You will die"
I think this is better stated as "You can die, and it may be at an inopportune or 'dramatically inconvenient moment'" In other words, being a PC doesn't grant them immunity from grave consequences.
"And lastly, "you will die" gives me the issue that... narratively, death is the least interesting thing that could happen. If a character dies, that's the end for them. There's no further drama, laughs or tragedy to be had. It's on this point that I don't think OSR games should really call themselves role-playing games, if this is their focus. They are very much games, but if cycling through multiple characters that die is the point, and its focused on what players can do rather than what characters can do, all those points together make it feel more like a board game with less rules than a role-playing game."
I agree that death as a consequence is one of the least interesting consequences, along with no lasting or serious consequences. I personally have PCs being down at 0 hp in a state of uncertainty until another PC comes to check them with a check penalized by time since 0 hp. and I've also offered other consequences of being downed like dismemberment and the like. Oddly, I've never had any players take me up on that, not even letting me get to actual possibilities of it; choosing death and reroll.
And like David says, I really don't think that even at a basic level, both in rules and in actual play, for death to be a permanent discontinuity in a narrative, such as you can have in D&D. To me it feels like a reaction to the continuous ease of surviving death and the 'Level Appropriate CR Encounter' mode of 3e onward. Which is as the default CR equal to Average Level is basically 4:1 odds favoring the players. The immediate risk PC death is minimal by design.
There is the play-style of each PC also has a henchperson as well as hirelings which should the PC fall could become the newest PC, maintaining a certain amount of continuity through the shared experiences the previously NPC had with the party and their relationship with the slain.
There is the erase or add a suffix to the PC's name retaining all stats making death to be more of an inconvenience, and in the case of a suffixed name, or even a new name, the 'new' PC is a relation to the prior, with any and all prehistory between them and the drama of "oh my dear sweet dead relation." As well as the rolling up a new character and gaining an inheritance.
In these cases, yes the PC is dead, but their death is added to the collective's story.
This does ignore the constantly dying at level one situation which means there is can be very little growth and continuity, which is a complaint that is made. This is also where the rewrite the name on the sheet thing most frequently comes into play.
But more importantly, IMO, than these ways of creating continuity through or despite PC death, is that within the Cook/Marsh Expert D&D book it says to make sure the starting town has some kind of temple with a cleric of sufficient power to cast Raise Dead. The Moldvay Basic book doesn't because it doesn't include spells of high enough level. And these two books, B/X, are one of the main editions of D&D to have OSR games based on.
"You Will Die" should be "Death is a real consequence." And it's more of an immediate consequence of reckless action and an acknowledgement that PCs aren't necessarily favored by fate.